Resistance of Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis to nitric oxide correlates with disease severity in Tegumentary Leishmaniasis

BACKGROUND: Nitric oxide (NO(•)) plays a pivotal role as a leishmanicidal agent in mouse macrophages. NO(• )resistant Escherichia coli and Mycobacterium tuberculosis have been associated with a severe outcome of these diseases. METHODS: In this study we evaluated the in vitro toxicity of nitric oxide for the promastigote stages of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis parasites, and the infectivity of the amastigote stage for human macrophages. Parasites were isolated from patients with cutaneous, mucosal or disseminated leishmaniasis, and NO(• )resistance was correlated with clinical presentation. RESULTS: Seventeen isolates of L. (L.) amazonensis or L. (V.) braziliensis promastigotes were killed by up to 8 mM of more of NaNO(2 )(pH 5.0) and therefore were defined as nitric oxide-susceptible. In contrast, eleven isolates that survived exposure to 16 mM NaNO(2 )were defined as nitric oxide-resistant. Patients infected with nitric oxide-resistant Leishmania had significantly larger lesions than patients infected with nitric oxide-susceptible isolates. Furthermore, nitric oxide-resistant L. (L.) amazonensis and L. (V.) braziliensis multiplied significantly better in human macrophages than nitric oxide-susceptible isolates. CONCLUSION: These data suggest that nitric oxide-resistance of Leishmania isolates confers a survival benefit for the parasites inside the macrophage, and possibly exacerbates the clinical course of human leishmaniasis

HELICOBACTER PYLORI INFECTION AND GASTRIC CANCER PRECURSOR LESIONS: PREVALENCE AND ASSOCIATED FACTORS IN A REFERENCE LABORATORY IN SOUTHEASTERN BRAZIL

ABSTRACT BACKGROUND: Helicobacter pylori infection is the most important risk factor for gastric atrophy and intestinal metaplasia, both considered gastric cancer precursor lesions. Therefore, the investigation of the occurrence of H. pylori infection, precursor lesions and associated factors guides the adoption of specific strategies for the control this type of cancer. OBJECTIVE: To evaluate the prevalence of H. pylori infection in patients undergoing upper digestive endoscopy, as well as the prevalence of intestinal metaplasia, atrophy and chronic inflammation and their association with H. pylori infection. METHODS: A retrospective study was performed based on reports of gastric endoscopic biopsies performed in a private laboratory affiliated to the Brazilian Public Health System (SUS). Patients were evaluated for age, gender and type of health service. The samples were evaluated for the presence of H. pylori, and also of chronic inflammation, intestinal metaplasia and glandular atrophy. RESULTS: Of a total of 4,604 patients (mean age 51±16.6), 63.9% were female and 63.1% coming from private health care service. The prevalence of H. pylori infection was 31.7% (n=1,459), and the percentage of infection was significantly higher in patients from public health service (42.0%) in relation to patients from private health service (25.6%). Among H. pylori (+) patients, a higher percentage of intestinal metaplasia (17.7% vs 13.3%) and glandular atrophy (17.6% vs 6.9%) were observed when compared to those H. pylori (-) (P&lt;0.01). From the patients H. pylori (+) with at least one type of precursor lesion (n=418), 161 (38.5%) had metaplasia and chronic inflammation, 160 (38.3%) had atrophy and chronic inflammation and finally 97 (23.2%) presented metaplasia, atrophy and chronic inflammation simultaneously. CONCLUSION: The present study reinforces the association of H. pylori infection with gastric cancer precursor lesions in a Brazilian population, emphasizing the importance of infection prevention measures, as well as the treatment of infected patients, especially in regions with lower socioeconomic levels that show a higher prevalence of infection by H. pylori.</jats:p

Cytochrome c oxidase subunit 1 gene as a DNA barcode for discriminating Trypanosoma cruzi DTUs and closely related species

Abstract Background The DNA barcoding system using the cytochrome c oxidase subunit 1 mitochondrial gene (cox1 or COI) is highly efficient for discriminating vertebrate and invertebrate species. In the present study, we examined the suitability of cox1 as a marker for Trypanosoma cruzi identification from other closely related species. Additionally, we combined the sequences of cox1 and the nuclear gene glucose-6-phosphate isomerase (GPI) to evaluate the occurrence of mitochondrial introgression and the presence of hybrid genotypes. Methods Sixty-two isolates of Trypanosoma spp. obtained from five of the six Brazilian biomes (Amazon Forest, Atlantic Forest, Caatinga, Cerrado and Pantanal) were sequenced for cox1 and GPI gene fragments. Phylogenetic trees were reconstructed using neighbor-joining, maximum likelihood, parsimony and Bayesian inference methods. Molecular species delimitation was evaluated through pairwise intraspecific and interspecific distances, Automatic Barcode Gap Discovery, single-rate Poisson Tree Processes and multi-rate Poisson Tree Processes. Results Both cox1 and GPI genes recognized and differentiated T. cruzi, Trypanosoma cruzi marinkellei, Trypanosoma dionisii and Trypanosoma rangeli. Cox1 discriminated Tcbat, TcI, TcII, TcIII and TcIV. Additionally, TcV and TcVI were identified as a single group. Cox1 also demonstrated diversity in the discrete typing units (DTUs) TcI, TcII and TcIII and in T. c. marinkellei and T. rangeli. Cox1 and GPI demonstrated TcI and TcII as the most genetically distant branches, and the position of the other T. cruzi DTUs differed according to the molecular marker. The tree reconstructed with concatenated cox1 and GPI sequences confirmed the separation of the subgenus Trypanosoma (Schizotrypanum) sp. and the T. cruzi DTUs TcI, TcII, TcIII and TcIV. The evaluation of single nucleotide polymorphisms (SNPs) was informative for DTU differentiation using both genes. In the cox1 analysis, one SNP differentiated heterozygous hybrids from TcIV sequences. In the GPI analysis one SNP discriminated Tcbat from TcI, while another SNP distinguished TcI from TcIII. Conclusions DNA barcoding using the cox1 gene is a reliable tool to distinguish T. cruzi from T. c. marinkellei, T. dionisii and T. rangeli and identify the main T. cruzi genotypes